Differential controls of water input on litter decomposition and nitrogen dynamics in the patagonian steppe

Laura Yahdjian, Osvaldo E. Sala, Amy T. Austin

Research output: Contribution to journalArticle

104 Scopus citations

Abstract

Studies of the effects of precipitation on litter decomposition and nitrogen mineralization in arid and semiarid environments have demonstrated contradictory results. We conducted a manipulative experiment with rainout shelters in the semi-arid Patagonian steppe, aimed at assessing the direct effects of water availability on litter decomposition and net nitrogen mineralization while isolating the indirect effects. We created four levels of precipitation input: control and three levels (30, 55 and 80%) of precipitation interception and we examined litter decomposition and nutrient release of a dominant grass species, Stipa speciosa, inorganic soil nitrogen, and in situ net nitrogen mineralization over two consecutive years. Litter decomposition rates (k, year-1) varied significantly (P < 0.001) among precipitation interception treatments and were positively correlated with incoming annual precipitation (APPT, mm/year) (k = 0.0007 x APPT + 0.137). In contrast, net N mineralization was not correlated with incoming precipitation. Soil NO 3- significantly decreased with increasing precipitation input, whereas soil NH4+ concentration did not differ among precipitation interception treatments. Controls of water input on litter decomposition appear to be different from controls on N mineralization in the semiarid Patagonian steppe. We suggest that although water availability affects both the mineralization of C and N, it differentially affects the movement and fate of the inorganic products. A consequence of the accumulation of inorganic N during dry episodes is that periods of maximum water and soil nutrient availability may occur at different times. This asynchrony in the availability of N and water in the soil may explain the observed lags in the response of primary production to increases in water availability.

Original languageEnglish (US)
Pages (from-to)128-141
Number of pages14
JournalEcosystems
Volume9
Issue number1
DOIs
StatePublished - Feb 1 2006
Externally publishedYes

Keywords

  • Arid ecosystems
  • Decomposition
  • Net N mineralization
  • Patagonian steppe (Argentina)
  • Phosphorus and nitrogen release
  • Rainfall interception
  • Rainout shelter
  • Soil NO and NH
  • Stipa speciosa
  • Water manipulations

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Environmental Chemistry
  • Ecology

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